This invention relates in general to a sealing ring construction and more particularly to the components of fluid seal assemblies used to provide inner diameter and outer diameter sealing on oil field equipment.
It is common practice to use seal assemblies to form a fluid barrier on the inner diameter or exterior diameter of oil field equipment, such as gas lift valves, safety valves, and circulating tools. Typically, a seal assembly includes a center element, one or more sealing rings, and one or more backup rings. The sealing rings typically are V-shaped or Chevron type packing rings, which have a concave, V-shaped bottom surface, a convex top surface and straight sides. Such rings are commonly known as V-rings. An example of such an assembly is shown in U.S. Pat. No. 4,811,959. Multiple V-rings may be necessary to provide a sufficient number of sealing surfaces for an effective seal.
The service conditions for seal assemblies can vary widely in temperature, pressure and the type of liquid or gas being sealed. Temperatures can range from -70.degree. F. to 400.degree. F., with pressures from atmosphere to 20,000 psi. To accommodate the varying service conditions, various materials and combinations of rings and backup rings are used. U.S. Pat. No. 4,811,959 describes a large variety of ring materials including fabric impregnated with rubber, asbestos with a plastic binder or elastomeric material, wire mesh, asbestos cord, ceramic fibers, and elastomeric materials wrapped with tetrafluoroethylene-propylene copolymer or terpolymer.
Multiple non-elastomeric backup rings may be used to give strength to the sealing rings in order to accommodate high pressures. Often, when the seal assembly is taken apart and reassembled for repair or other reasons, the backup rings are inadvertently left out or too few backup rings are replaced. Error in installation of the backup rings can result in excessive deformation and destruction of the V-rings and substantial wear, inefficient operation and leakage of the seal.
In view of the foregoing, a need exists for a seal assembly which can accommodate high pressures without the need for backup rings. Also, a need exists for a seal assembly which reduces the number of sealing rings necessary to provide an effective seal.